BOMBARDIER BEETLES (for origin of name, see below). Ground-beetles, Carabidæ, of the genus Brachinus. They are black, green, or blue beetles, with reddish-yellow legs. They live on the surface of the ground, and when closely pursued by an enemy, such as a predatory beetle, they discharge from the anus, with an explosive sound, a drop of fluid which turns to visible smoke-like gas on contact with the air. By the time the pursuer has recovered from astonishment and the inconvenience of this gas, the bombardier has frequently made good its escape; but, if needful, the discharge can be quickly repeated several times. When the reservoir which contains it is opened by dissection, the liquid effervesces and evaporates instantaneously. It changes blue vegetable colors to red, and then to yellow; produces sharp pain when applied to the tongue, and leaves a yellow spot upon its surface like that produced by a drop of nitric acid. There are about twenty-five species in the United States. See Ground-Beetle.